The invention relates to apparatus for providing a folded thermoplastic film with open side margins movable in a linear direction to receive a product between the folded plies of the film so that the open side edges of the film plies can be sealed in advance of cross sealing the film at the leading and trailing ends of each product.
The wrapping of products in a thermoplastic film is well known in the prior art represented by Watanaba U.S. Pat. No. 4,939,889 of Jul. 10, 1990 and by prior examples of apparatus such as Shanklin et al. U.S. Pat. No. 4,219,988 of Sep. 2, 1980, or Monaghan Re 27977 of Apr. 23, 1974. The apparatus of these items of prior art offer difficulties in moving the wrapping film at economical speed, and the apparatus is subject to mechanical stress when operated at speeds that meet needs of the product wrapping industry.